This invention relates generally to automatic dishwashers and, more specifically, to an improved control system which gives continuous protection against overfill flooding irrespective of whether the dishwasher is in use or standing idle.
Operation of conventional automatic dishwashers typically involves one or more pre-rinse periods, a wash period, and possibly one or more post-rinse periods. Frequently, there is also a drying period which may include the addition of heat to the wash chamber as a means of expediting drying.
Control means are provided to sequentially energize and de-energize the various electrically-operated components of the automatic dishwasher to perform the above-described operational cycle. Usually, a sequence control device having a timer motor and several cam-operated switches is provided with each switch controlling one of the components.
Unfortunately, however, such a sequence control device makes no provision for the unexpected failure of various components. Specifically, avoidance of overflow or flooding is a potential threat, resulting from failure of any of a number of components.
Flooding control systems have been provided in the past. U.S. Pat. No. 3,876,338 is an example of such a system wherein overflow is prevented by providing a unidirectional pump system for both recirculation and draining. This function is accomplished by selectively air-locking the drain pump during the recirculation operation to prevent draining of the tub at that time. However, the invention of U.S. Pat. No. 3,876,338 does not protect against fill valve failure while the dishwasher is sitting idle.
The invention of this disclosure overcomes the objections inherent in prior art machines and provides a 24 hour flood control protection device for dishwashers.